1. Technical Field
Embodiments of the present disclosure relate to optical devices and methods for adjusting the optical devices, and particularly to a projector and a method for correcting trapezoid distortion of an image projected by the projector.
2. Description of Related Art
Projectors can project an original image on a screen. When a projector is installed in such a manner that an optical axis of a projection lens of the projector accords with a normal line of the screen, a projected image similar to the original image is projected as a normal rectangular picture on the screen without a trapezoid distortion. The trapezoid distortion is also called a keystone distortion that is defined as a type of geometric distortion where the vertical edges of the projected image slant inwards towards the top horizontal edge.
Projectors are generally installed on a place where the projector does not accord with the normal line of the screen, for instance, on a floor, or on a ceiling in a suspended state. In such a case, the trapezoid distortion may occur on the projected image. To avoid the trapezoid distortion on the projected image, various kinds of countermeasures have been proposed, such as an optical compensation method. However, there is a problem that the production cost of the projector becomes very high, and it is difficult to obtain a largely magnified projected image having a high quality.